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https://dev.mysql.com/doc/internals/en/optimizer-trace-testing.html
This feature is tested in mysql-test/suite/opt_trace and unittest/gunit/opt_trace-t. ...
https://dev.mysql.com/doc/internals/en/optimizer-tracing-typical-usage.html
# Turn tracing on (it's off by default): SET optimizer_trace="enabled=on"; SELECT ...; # your query here SELECT * FROM INFORMATION_SCHEMA.OPTIMIZER_TRACE; # possibly more queries... # When done with tracing, disable it: SET ...
https://dev.mysql.com/doc/internals/en/optimizer-transpositions.html
MySQL supports transpositions (reversing the order of operands around a relational operator) for simple expressions only. In other words: WHERE - 5 = column1 becomes: WHERE column1 = -5 However, MySQL does not support transpositions where ...
https://dev.mysql.com/doc/heatwave/en/mys-hwaml-ml-metrics.html
The ML_TRAIN routine includes the optimization_metric option, and the ML_SCORE routine includes the metric option. Both of these options define a metric that must be compatible with the task type and the target data. precision_k: An Oracle ...
https://dev.mysql.com/doc/refman/8.4/en/innodb-performance-ro-txn.html
InnoDB can avoid the overhead associated with setting up the transaction ID (TRX_ID field) for transactions that are known to be read-only. A transaction ID is only needed for a transaction that might perform write operations or locking reads such ...
https://dev.mysql.com/doc/refman/8.4/en/locking-issues.html
MySQL manages contention for table contents using locking: Internal locking is performed within the MySQL server itself to manage contention for table contents by multiple threads. This type of locking is internal because it is performed entirely ...
https://dev.mysql.com/doc/refman/8.4/en/optimize-benchmarking.html
To measure performance, consider the following factors: Whether you are measuring the speed of a single operation on a quiet system, or how a set of operations (a “workload”) works over a period of time. With simple tests, you usually test how ...
https://dev.mysql.com/doc/mysql-enterprise-backup/8.4/en/restore-performance.html
This section describes the performance considerations for restoring a database server with MySQL Enterprise Backup. This subject is important because: The restore operation is the phase of the backup-restore cycle that tends to vary substantially ...
https://dev.mysql.com/doc/mysql-monitor/8.0/en/glossary.html
Performance monitoring involves checking whether queries that are slow or frequently run could be sped up or made less resource-intensive, by examining the EXPLAIN plan to check if the MySQL optimizer has chosen the most efficient ways to process ...
https://dev.mysql.com/doc/refman/8.4/en/controlling-query-plan-evaluation.html
The task of the query optimizer is to find an optimal plan for executing an SQL query. Because the difference in performance between “good” and “bad” plans can be orders of magnitude (that is, seconds versus hours or even days), most query ...For small numbers of tables (typically less than 7 to 10) this is not a ...